﻿<p><em>IfcConstructionMaterialResource</em> identifies a material resource type in a construction project.</p> 

<blockquote class="history">
HISTORY&nbsp; New entity in IFC2.0.
</blockquote>

<blockquote class="change-ifc2x4">
IFC4 CHANGE&nbsp; The attribute <em>Suppliers</em> has been deleted; use <em>IfcRelAssignsToResource</em> to assign an <em>IfcActor</em> to fulfill the role as a supplier.  The attribute <em>UsageRatio</em> has been deleted; use <em>BaseQuantityConsumed</em> and <em>BaseQuantityProduced</em> to indicate material usage.
</blockquote>

<p>Occurrences of <em>IfcConstructionMaterialResource</em> are consumed (wholly or partially), or occupied during a construction work task (<em>IfcTask</em>).</p> 

<p>Similar to <em>IfcConstructionProductResource</em>, sometimes things such as 5000kg of gravel are already instantiated as an instance of an <i>IfcProduct</i> subtype because it is a result of a work task (for example, &#145;transporting gravel&#146;). In this case, the instance of <em>IfcConstructionMaterialResource</em> can be associated with the product instance &#145;5000kg of gravel&#146; to provide more information for resource uses. Nevertheless, <em>IfcConstructionMaterialResource</em> should only be used to represent resource usage, but not product substances.</p> 

<blockquote class="note">NOTE&nbsp; 
This entity is not the same as <i>IfcMaterial</i>.  One one hand, 
<i>IfcConstructionMaterialResource</i> represents usage of bulk materials 
such as sand, gravels, nails and so on.  Physical manifestations can be instantiated from 
<i>IfcProduct</i> as well, depending on their uses in the system, and such an 
<i>IfcProduct</i> object can be assigned to the <i>IfcConstructionMaterialResource</i> 
object via <i>IfcRelAssignsToResource</i>.  On the other hand, <i>IfcMaterial</i> is 
about physical materials that a physical building element consists of, 
possibly with detailed material layering information."
</blockquote>